A saxophone quartet generally is made up of a soprano saxophone, an alto saxophone, a tenor saxophone, and a baritone saxophone.  It can also have two altos, one tenor, and a baritone.  Occasionally they will use bass saxophones or other varieties even.

Arrangements have been written for many jazz pieces and classical pieces.  Here are two videos of saxophone quartets.

Above- World Saxophone Quartet playing ‘Hattie Wall’

Rhapsody in Blue by Gershwin